Inside calipers or gage



(No Model.)

J. A. BLAIR.

INSIDE GALIPERS 011 GAGE.

' Patented Jan. 15, 1889.

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JOHN A. BLAIR, OF PHILADELPHIA, PENNSYLVANIA.

INSIDE CALIPERS OR GAGE.

SPECIFICATION forming part of Letters Patent No. 396,064, datedJ'anuary 15, 1889.

Application filed August 4, 1888. Serial No. 282,005. (No model.)

To aZZ whom it may concern:

zen of the United States, residing in the city and county of Philadelphia, State of Pennsylvania, have invented a new and useful Improvement in Inside Calipers or Gages, which improvement is fully set forth in the following specification and accompanying drawings.

My invention relates particularly to meas nring-instruments or calipers designed for measuring the interior diameters of cylinders, bands, collars, &c. 5 and to this end it consists in details of construction hereinafter described, and particularly pointed out in the claims which follow this specification. It will be fully understood by referring to the accompanying drawings, in which I Figure 1 represents a side elevation of a calipers embodying my invention, partly in section. Fig. 2 represents a longitudinal section of the adjustable parts. Figs. 3 and i represent detail views of the same.

Similar letters of reference indicate corresponding parts in the several figures.

A represents a hollow metallic sleeve having a metal plug, K, in one end, with a pointed end, i, and B represents a metal rod adapted to slide smoothly within said sleeve until its inner end comes against the plug K. This rod has also a pointed end, c, similar to the point 'i.

0 represents a metal clamp composed of a suitable piece of material, one end being provided with a female screw-thread, 0, adapted to the male screw-thread on the end of the sleeve A, as shown in Fig. 2. These screw portions are adjustably held together by a split collar, D, integral with the part C, and the adjustment is effected by a thumb-screw, E, having a milled head. An additional screw, H, with milled head, is provided for firmly sesuring the parts 0 and I3 together, when desired.

This tool is used in the following manner: The interior diameter to be measured is first approximated by inserting the adjustable calipers inside the cylinder, band, or collar to be measured, and drawing the part B out of the sleeve A until the ends e and 2' nearly touch the sides thereof. The screw H is then firmly set against the rod 13, and the parts B and A rotated in opposite directions until the points 6 and i touch the opposite sides or walls. The screw E, with milled head, is then turned so as to firmly fixthe parts 0 and A together, and the exact reading taken from the scale a marked on the surface of A, and indicated by pointer or hand P.

I am aware that extensible interior calipers are old, and I do not claim such, broadly; but in the present invention the measuring may be taken with great precision, as the scale a on the sleeve has its marks extending parallel with the length of the same, and separated such distance that the extent of the rotation of the sleeve from mark to mark is equal to the thickness of a piece of paper, or a fraction thereof, or maybe equal to more than one piece of paper, so that the use of paper, as heretofore practiced, may be dispensed with, and an instrument for delicate and correct adjustment is presented.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. An interior calipers consisting of a tube having an exteriorlyscrew-threaded end with a rod adapted to slide in said end, and a sleeve secured to said rod and adapted to rotate on the screw-tlnread ed end of said tube, and having a collar with clamping-screw whereby said sleeve is secured in place on said tube, substantially as described.

2. An interior calipers consisting of the tube A, wit-h an exteriorlyscrew-threaded end, the plug K, adapted to lit in the other end of the tube A and having a pointed end, a rod adapted to slide in the screw-threaded end of the tube and having a pointed outer end, the sleeve 0, with split collar I) and screw E, and the screw H securing said collar to the said sliding rod, said parts being combined substantially as and for the purpose set forth.

3. The described measuring-tool or interior calipers, consisting of two extensible parts adapted to slide the one within the other, in combination with a connecting-sleeve having a set-screw for securing one of said extensible parts and an interiorly-screw-threaded collar with set-screw attachment for secursecuringsaid parts together, snhsmntially as desorilmd JOHN A. BLAIR.

\Vitnesses: V

JOHN A. XVIEDERSHEIM, ROBT. AITON. 

